/*
 * libusb synchronization on Microsoft Windows
 *
 * Copyright (C) 2010 Michael Plante <michael.plante@gmail.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <config.h>
#include <objbase.h>
#include <errno.h>
#include <stdarg.h>

#include "libusbi.h"


int usbi_mutex_init(usbi_mutex_t *mutex,
                    const usbi_mutexattr_t *attr) {
    if(! mutex) return ((errno=EINVAL));
    *mutex = CreateMutex(NULL, FALSE, NULL);
    if(!*mutex) return ((errno=ENOMEM));
    return 0;
}
int usbi_mutex_destroy(usbi_mutex_t *mutex) {
    // It is not clear if CloseHandle failure is due to failure to unlock.
    //   If so, this should be errno=EBUSY.
    if(!mutex || !CloseHandle(*mutex)) return ((errno=EINVAL));
    *mutex = NULL;
    return 0;
}
int usbi_mutex_trylock(usbi_mutex_t *mutex) {
    DWORD result;
    if(!mutex) return ((errno=EINVAL));
    result = WaitForSingleObject(*mutex, 0);
    if(result == WAIT_OBJECT_0 || result == WAIT_ABANDONED)
        return 0; // acquired (ToDo: check that abandoned is ok)
    if(result == WAIT_TIMEOUT)
        return ((errno=EBUSY));
    return ((errno=EINVAL)); // don't know how this would happen
                             //   so don't know proper errno
}
int usbi_mutex_lock(usbi_mutex_t *mutex) {
    DWORD result;
    if(!mutex) return ((errno=EINVAL));
    result = WaitForSingleObject(*mutex, INFINITE);
    if(result == WAIT_OBJECT_0 || result == WAIT_ABANDONED)
        return 0; // acquired (ToDo: check that abandoned is ok)
    return ((errno=EINVAL)); // don't know how this would happen
                             //   so don't know proper errno
}
int usbi_mutex_unlock(usbi_mutex_t *mutex) {
    if(!mutex)                return ((errno=EINVAL));
    if(!ReleaseMutex(*mutex)) return ((errno=EPERM ));
    return 0;
}

int usbi_mutex_static_lock(usbi_mutex_static_t *mutex) {
    if(!mutex)               return ((errno=EINVAL));
    while (InterlockedExchange((LONG *)mutex, 1) == 1) {
        SleepEx(0, TRUE);
    }
    return 0;
}
int usbi_mutex_static_unlock(usbi_mutex_static_t *mutex) {
    if(!mutex)               return ((errno=EINVAL));
    *mutex = 0;
    return 0;
}



int usbi_cond_init(usbi_cond_t *cond,
                   const usbi_condattr_t *attr) {
    if(!cond)           return ((errno=EINVAL));
    list_init(&cond->waiters    );
    list_init(&cond->not_waiting);
    return 0;
}
int usbi_cond_destroy(usbi_cond_t *cond) {
    // This assumes no one is using this anymore.  The check MAY NOT BE safe.
    struct usbi_cond_perthread *pos, *prev_pos = NULL;
    if(!cond) return ((errno=EINVAL));
    if(!list_empty(&cond->waiters)) return ((errno=EBUSY )); // (!see above!)
    list_for_each_entry(pos, &cond->not_waiting, list, struct usbi_cond_perthread) {
        free(prev_pos);
        list_del(&pos->list);
        prev_pos = pos;
    }
    free(prev_pos);

    return 0;
}

int usbi_cond_broadcast(usbi_cond_t *cond) {
    // Assumes mutex is locked; this is not in keeping with POSIX spec, but
    //   libusb does this anyway, so we simplify by not adding more sync
    //   primitives to the CV definition!
    int fail = 0;
    struct usbi_cond_perthread *pos;
    if(!cond)                      return ((errno=EINVAL));
    list_for_each_entry(pos, &cond->waiters, list, struct usbi_cond_perthread) {
        if(!SetEvent(pos->event))
            fail = 1;
    }
    // The wait function will remove its respective item from the list.
    return fail ? ((errno=EINVAL)) : 0;
}
int usbi_cond_signal(usbi_cond_t *cond) {
    // Assumes mutex is locked; this is not in keeping with POSIX spec, but
    //   libusb does this anyway, so we simplify by not adding more sync
    //   primitives to the CV definition!
    struct usbi_cond_perthread *pos;
    if(!cond)                      return ((errno=EINVAL));
    if(list_empty(&cond->waiters)) return 0; // no one to wakeup.
    pos = list_entry(&cond->waiters.next, struct usbi_cond_perthread, list);
    // The wait function will remove its respective item from the list.
    return SetEvent(pos->event) ? 0 : ((errno=EINVAL));
}
static int __inline usbi_cond_intwait(usbi_cond_t *cond,
                                      usbi_mutex_t *mutex,
                                      DWORD timeout_ms) {
    struct usbi_cond_perthread *pos;
    int found = 0, r;
    DWORD r2,tid = GetCurrentThreadId();
    if(!cond || !mutex) return ((errno=EINVAL));
    list_for_each_entry(pos, &cond->not_waiting, list, struct usbi_cond_perthread) {
        if(tid == pos->tid) {
            found = 1;
            break;
        }
    }
    if(!found) {
        //pos      = (struct usbi_cond_perthread*) calloc(1, sizeof(struct usbi_cond_perthread));
        pos      = (struct usbi_cond_perthread*) malloc(sizeof(struct usbi_cond_perthread));
        memset(pos, 0x00, sizeof(struct usbi_cond_perthread));
        if(!pos) return ((errno=ENOMEM)); // This errno is not POSIX-allowed.
        pos->tid = tid;
        pos->event = CreateEvent(NULL, FALSE, FALSE, NULL); // auto-reset.
        if(!pos->event) {
            free(pos);
            return      ((errno=ENOMEM));
        }
        list_add(&pos->list, &cond->not_waiting);
    }

    list_del(&pos->list); // remove from not_waiting list.
    list_add(&pos->list, &cond->waiters);

    r  = usbi_mutex_unlock(mutex);
    if(r) return r;
    r2 = WaitForSingleObject(pos->event, timeout_ms);
    r  = usbi_mutex_lock(mutex);
    if(r) return r;

    list_del(&pos->list);
    list_add(&pos->list, &cond->not_waiting);

    if(r2 == WAIT_TIMEOUT) return ((errno=ETIMEDOUT));

    return 0;
}
// N.B.: usbi_cond_*wait() can also return ENOMEM, even though pthread_cond_*wait cannot!
int usbi_cond_wait(usbi_cond_t *cond, usbi_mutex_t *mutex) {
    return usbi_cond_intwait(cond, mutex, INFINITE);
}
int usbi_cond_timedwait(usbi_cond_t *cond,
                        usbi_mutex_t *mutex,
                        const struct timespec *abstime) {
    FILETIME filetime;
    ULARGE_INTEGER rtime;
    struct timeval targ_time, cur_time, delta_time;
    struct timespec cur_time_ns;
    DWORD millis;
    extern const uint64_t epoch_time;

    GetSystemTimeAsFileTime(&filetime);
    rtime.LowPart   = filetime.dwLowDateTime;
    rtime.HighPart  = filetime.dwHighDateTime;
    rtime.QuadPart -= epoch_time;
    cur_time_ns.tv_sec = (long)(rtime.QuadPart / 10000000);
    cur_time_ns.tv_nsec = (long)((rtime.QuadPart % 10000000)*100);
    TIMESPEC_TO_TIMEVAL(&cur_time, &cur_time_ns);

    TIMESPEC_TO_TIMEVAL(&targ_time, abstime);
    timersub(&targ_time, &cur_time, &delta_time);
    if(delta_time.tv_sec < 0) // abstime already passed?
        millis = 0;
    else {
        millis  = delta_time.tv_usec/1000;
        millis += delta_time.tv_sec *1000;
        if (delta_time.tv_usec % 1000) // round up to next millisecond
            millis++;
    }

    return usbi_cond_intwait(cond, mutex, millis);
}

